Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)(2)(H(2)O)]· 4H(2)O, [Mn(Phen)(2)(H(2)O)(2)](2)(Isoph)(2)(Phen)· 12H(2)O and {[Mn(Isoph)(bipy)](4)· 2.75biby}(n)(phH(2) = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine)

Manganese(II) acetate reacts with phthalic acid (phH(2)) to give [Mn(ph)]·0.5H(2)O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)]·2H(2)O (2) and [Mn(ph)(phen)(2)(H(2)O)]·4H(2)O (3). Reaction of isophthalic acid (isophH(2)) with manganese(II) acetate results in the formation of [Mn(isoph)]·2H(2)O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn(2) (isoph)(2)(phen)(3))]·4H(2)O (5), [(Mn(phen)(2)(H(2)O)(2)](2)(isoph)(2)(phen)·12H(2)O (6) and {[Mn(isoph)(bipy)](4)·2.75 biby}(n) (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the “metal free” 1,10-phenanthroline and its manganese complexes were found to be active.